Urological resectoscopes are primarily used for prostate resections, though, depending on the particular design, they also may be used for other surgical purposes. Herein the concept of “resectoscope” denotes endoscopic instruments wherein an optics and an electrode support, together with a distal electrode, are configured in a stem tube and wherein the electrode support jointly with the electrode is configured in an axially displaceable manner. The support is affixed at its proximal end to a resectoscope slide block with which it makes electric contact, the slide block being axially displaceable by manually driving a grip in order to axially displace the electrode.
During prostate resection, the distal stem tube end of the resectoscope is advanced through the urethra inside the prostrate. When hf is applied to the electrode, the electrode may be advanced and retracted by manually driving the slide block in order to cut tissue. In general, the electrode is configured as a wire loop to trim tissue snippets. Furthermore, the electrode may assume other geometries, for instance being a button electrode, a roller electrode, a knife electrode or the like, in order to allow application to different purposes, such as coagulation, cutting or the like.
Problems are encountered as regards the appropriate contact between the electrical conductor feeding the electrode and the slide block site it touches. At this contact zone of the conductor, the contact must be implemented by a further cable leading to a separate hf generator. HF loaded contacts are problematical and are susceptible to defects or damage, such as scorching.
In older designs, a tightening screw simultaneously sets up the contact and the mechanical affixation of the electrode support inside the slide block. Once such a contact site chars, the full slide block must be replaced.
The WO 96/234449 patent document, as shown by its FIG. 16, which is outside the species discussed herein, concerns a bipolar-electrode resectoscope. In other words, two electrical conductors cross the electrode support. Consequently, the electrode support is fitted with two contact zones in the region of the slide block. A plug-element affixed to the slide block and fitted on the continuing cable implements contact both contacting zones and, hence, simultaneously implements the contacting function and mechanical clamping. A special and separate fastener is not provided. Accordingly, in this design contacting and clamping will always be simultaneous. This design precludes affixing the electrode support, for the purpose of testing the mechanical operation, prior to setting up the contact(s).
A design of the kind disclosed herein is known from U.S. Pat. Nos. 4,917,621 and 4,919,131, each shown in their particular FIG. 3. The slide block therein is fitted with a transversely continuous duct receiving the continuing hf cable's plug element, which makes contact with the electrode support's contact zone freely resting in the duct. A clamping element is present distally from the duct and acts on a fastening segment of the electrode support.
This design offers the advantage to separately affix in mechanical manner the electrode support and the clamping element on the slide block, as a result of which it is possible to first check this slide block's proper mechanical operation. Thereupon, contact may be implemented with the plug. If the contact site should char, only the electrode support and the cable together with the plug need be changed. The clamping element and the slide block on the other hand remain intact because the clamping element is separate.
However, the known design of the above species does entail drawbacks.
Because the affixation device is configured distally from the contacting element, the electrode support site where affixation takes place is crossed by the electric conductor connecting the contacting site to the electrode. As a result the electrode support lacks mechanical strength in this region. The affixation device must allow for this lack of strength and illustratively may only operate with minute tightening forces. If affixation takes place by means of a slide block entering a groove and acting on the electrode support, then the groove may only be very shallow and consequently the reliability of affixation is considerably reduced.
The proximal end zone of the electrode support is constituted both by that zone wherein affixation takes place and by the contacting zone. These zones, namely the full end zone of the electrode support, therefore are rigid and more resistant to bending than the remainder of the electrode support, which consists only of an inner conductor and an outer insulation. In resectoscopes, however, the electrode support typically will be configured tightly against the optics inside the stem tube, whereas, in the region of the slide block, the support and optics must be farther apart in order to subtend enough space for the contacting system and the affixation device. Therefore, the electrode support must be pivotably supported inside the main block in the manner indicated, for instance, in FIG. 3 of the patent document WO 96/234449. However, the main block being required to be of moderate length on technical grounds, large pivoting must take place over a short path. Unfortunately, the considerable length of the rigid end region of the known electrode supports hampers such motion.
Moreover, assembly may be defective if the electrode support was insufficiently inserted and thereupon was fixed in place.